False positive pregnancy?

So I had unprotected sex with a girl in December. I am a very paranoid person so asked her to do a pregnancy test last Monday, she did two in the evening one came back positive the other negative.

The next morning we went to the doctors and did one there which came back negative, followed by another at a GUM clinic in the evening (after drinking allot of water) which came back negative.

Still paranoid she was pregnant we went back to the doctors on the Thursday and did another there which was negativity and they also took a urine sample to do a laboratory test which has also come back negative.

She does not get periods as she was on the injection, however she was late getting the injection around the time we had sex. Is there any chance she could be pregnant or am I safe to assume it was a false positive? The tests used were Clear Blue Digital, not cheap ones.

Can someone please help last couple days I've been really nausea tummy and back sore some days I wake up...bout a week ago I threw up in my mouth twice and I have mild cramps it feels like off and on....eating makes me nausea and sometimes thinking bout food makes me nausea so I haven't really been eating...but I've been really hungry but the thought of eating makes me sick I've also been really tired it seems like I'm moving really slow at work

Hey so I was wondering whether or not there is a possibility of pregnancy in my situation or whether I am just overthinkingI'm 18 years old, I've never had sex however I did engage in foreplay with my current boyfriend. He fingered me however I'm unsure as to whether he quickly adjusted himself before hand (we were both clothed). Therefore, I am worried as to whether he had Precum on his fingers before they went inside me (bearing in mind they may have been wiped due to the transfer having to go under my pants and down). If this is not enough, I did proceed to touch him and my hand was definitely wet but I was on his left side and so used my left hand. We then moved into another room which would obviously mean drying of the Precum as a possibility and once in there I did touch myself, however I think it was with my right hand as that is my natural hand but I cannot remember. He did not ejaculate at any point during this time however I think I was ovulating. It's been two weeks and my period is due tomorrow and idk I'm just worried that it won't arrive which would quite honestly be disastrous which I suppose is why I'm overthinking this. My periods are usually regular however my last one was three days early so I don't know whether that could mean that this one is a few days late in order to balance it? I'm not sure of these things. Usually I have a cycle of 28 days give or take a day or so on average.Any advice/ judgement of pregnancy chances would be very helpful to settle my mind if nothing else, thank you.